1. Field of the Invention
The present invention relates to a thermoplastic resin composition comprising four types of thermoplastic resins and having various excellent properties.
2. Description of the Related Art
Thermoplastic resins are used in various fields by utilizing respective properties of each resin. Materials having a higher performance have been recently discovered and proposed by mixing two or more resins of different types.
U.S. Pat. No. 4,246,374 (corresponding to GB 1,559,132) describes a method for producing a glutarimide polymer and a blend of this polymer with an ABS resin or MBS resin which is an impact resistance-improving agent. Japanese Patent Kokai Publication No. 41355/1984 describes a thermoplastic resin composition comprising a thermoplastic polyester, polyglutarimide and an impact modifier.
With respect to the blend of the glutarimide polymer and the impact resistance-improving agent described in U.S. Pat. No. 4,246,374, a content of the impact resistance-improving agent is increased and heat resistance which the glutarimide polymer possesses as its distinctive feature becomes poor when the still higher impact resistance is required. The resin composition described in Japanese Patent Kokai Publication No. 41355/1984 also has poor heat resistance and impact resistance.